The following discussion of the background of the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge in any jurisdiction as at the priority date of the application.
Conventional lighting systems typically have a configuration where light products used in the systems are individually driven. For example, a light product such as a down light lamp has its own in-built power supply or ballast which converts incoming AC electrical supply to higher AC voltage and desired current that is required to provide electrical power to for example ignite and excite the gases (referring to CFL light) for lighting up of the down light. Examples of such other light products include T5, T8, Light Troffer, High-Bay lamps, street lamps and flood lamps.
Similarly, when Light Emitting Diodes (LEDs) were introduced in lighting systems, the configuration adopted for LEDs was based on a similar ‘one-ballast (controller)’ to ‘one-lamp’ arrangement of conventional lighting systems. Therefore, each LED light unit has its own in-built LED driver or controller that converts the incoming AC supply to DC voltage and current to light up the LED down light. This means that each LED light unit that is present in a lighting system has an accompanying controller dedicated to that particular LED light unit for converting the incoming AC supply to DC voltage and current for lighting up that particular LED light unit, i.e. a chain of ten LED down lights in a lighting system will require correspondingly ten LED controller circuits. These LED controllers increase the cost and overall form factor of each lamp unit.
A prior art LED light unit and system is illustrated in FIG. 1 and FIG. 2 respectively. The LED lamp unit comprises an AC source supply via AC Input Terminal 4, an AC-DC LED driver 3, a LED light/lamp module 1 and heat sink 2.
When connected, AC electrical supply current will flow to the input of the AC-DC LED driver 3. The AC supply current will be rectified via switch mode power supply circuitry in the AC-DC LED driver 3 to supply the desired DC voltage and current to the LED light module 1. For continuous light-up operation, as heat will be generated by both the AC-DC LED driver 3 and the LEDs on the LED light module 1, introduction of heat sink 2 is important to ensure the heat generated along the light-up operation is drawn from the heat source and dissipated accordingly. The heat sink 2 has to account for heat dissipation from both the LED light module and AC-DC LED driver. Consequently, if at any time along the light-up operation the heat sink 2 reaches its maximum heat dissipation capability due to the design limitation in size for standard form factor for the particular LED lighting unit fulfillment will lead to the degradation of light performance and product life span.
The above-mentioned configuration has several disadvantages including:
As each LED light unit requires its own in-built controller circuit 3 for lighting up, when the LED light unit is in continuous operation, considerable heat will be generated by both the LED and controller circuit. To moderate the heat, heat sink(s) must be present in each LED light unit for drawing the heat from the heat source and dissipating the heat to the surroundings so as to provide a thermally cool environment for the LED and controller circuit to operate in. It is important that the LED and controller circuit operate in a thermally cool environment because this will reduce power loss and hence improve efficiency. However, due to standard form factors, there is a limit as to the size of the heat sink in each LED light unit. As there are two heat generating sources in each LED light unit (i.e. the LED lamp unit and the LED controller), the heat sink 2 typically reaches its maximum heat dissipation capability during continuous operation where considerable heat is generated. Consequently, this will lead to the degradation of the LED light unit's light performance and product life span.
It is typically costly to manufacture LED light units which have built-in controller circuits and heat sinks 2 as they increase the number of components that are needed for manufacture. Furthermore, the heat sink must also be designed to cope with the dissipation of heat from two heat sources with the constraints on its size due to standard form factors. This further increases the overall cost of producing the LED light units.
As the AC supply will be converted to DC voltage and current in the LED light units by the controller circuits 3, there will be safety related issues that must be addressed. Hence, the LED light units will have to be designed such that they meet the standard safety requirements and size limitations imposed by standard form factors.
Therefore, it is an object of the present invention to overcome, or at least alleviate, at least the aforementioned problems.